Limits to the Performance and Design of High Voltage Metalized Film Capacitors

The use of multiple sections within a metalized film capacitor facilitates high voltage and reduced equivalent series resistance within a compact winding. As a result of high voltage and low inductance, large peak currents are, in principle, possible. The limitation to the peak current and power density is the ability of the end connection to withstand the peak current. As a result, the power density of such capacitors is limited not by materials but by the end connection current density, and improved materials, such a capacitor films with greater dielectric constant, will not result in increased energy density as the limiting factor is the length of the end connection necessary to achieve the required peak current. The energy density of multisection windings is also limited by the margins which are required between sections, the total width of which is limited solely by the rated voltage and margin operating field. The margins cause a substantial reduction in energy density, especially when the overall design is dictated by end connection current density. These issues are explored and quantified.